VOIP is the short name of Voice over Internet Protocol, which is, in brief, used for digitizing a simulated voice signal and transmitting the digital signal over an IP network in a data packet form in real time. The basic principle of the VOIP is that voice data codes are compressed and packed using a voice compression algorithm so that the voice data can be transmitted to a target terminal over an IP network, and then the data packet is reconverted to the original voice signal through an inverse process for being received by a receiver. The VOIP has been proposed for more than ten years and has been greatly improved in both voice quality and Quality of Services (QoS) with development of technologies, in addition, with advantages of convenient deployment and low price, the VOIP has been already widely applied in all over the world.
Conventional CS telephone is one part of a Public Switched Telephone Network (PSTN) and adopts a fixed channel mode in which once a communication is established, a channel is occupied by the two parties of the communication till the communication is terminated.
At present, with wireless broadband network technology being gradually improved, Third-Generation (3G) and Beyond 3G (B3G) mobile communication systems have become increasingly available. Mobile communication operators in different countries are actively deploying domestically applicable broadband communication networks to attract more users with various services, and the combination of VOIP telephone with conventional CS telephone is one of the services. A gateway device of a family or medium/small-sized enterprises integrates gateway routing devices of Local Area Network (LAN), Wireless Local Area Network (WLAN), Wide Area Network (WAN) and so forth, and is therefore capable of providing an internal networking function to users and realizing the deployment of Internet services by making full use of bandwidth of a wireless broadband.
In prior art, independent VOIP or CS telephone function can be realized by a single device or gateway, however, the utilization ratio of the device is not ideal, and it is difficult to greatly enhance the value-adding capability of the device. Additionally, a gateway can be mounted with a two-path Subscriber Line Interface Circuit (SLIC) and connected with a fixed telephone using the bandwidth of a broadband and the conventional PSTN provided by a mobile communication operator. In this way, the functions of VOIP packet telephone and CS telephone for a family and an enterprise are realized on the same device or gateway, however, the functions of the two-path SLIC are fixed, that is, the two-path SLIC can only process their respective VOIP telephone voice code streams or CS telephone voice code streams, thereby leading to a complicated workflow of the whole system and a higher cost of the whole communication. Secondarily, due to the lack of a corresponding converter, existing device or gateway cannot make a selection on a transmission mode of a CS telephone voice code stream.